dtoc: Rename dt-platdata.c to dt-plat.c

Use this new name to be consistent with the rest of U-Boot, which talks
about 'plat' for the platform data, which is what this file holds.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 363f274..4a8e19e 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -262,7 +262,7 @@
  *	Defined below (keep this text to enable searching for spi_flash decl)
  * }
  */
-#ifndef DT_PLATDATA_C
+#ifndef DT_PLAT_C
 #define spi_flash spi_nor
 #endif